Facing such bad odds, it has never been more important for college students and recent grads to keep as much of their earnings as possible. Yet the U.S. Government Accountability Office reported that Americans left behind nearly $800 million in college tuition tax benefits in 2009 — an average of $466 per person.

With the national student debt near $1 trillion, it's a good time to revisit some of the most lucrative tax breaks out there for college students.

The American Opportunity Credit. Students are eligible to claim up to $2,500 for the first four years of post-secondary education. And since 40% of the credit is refundable, that means students can get back up to $1,000 on their refund — even if they don't owe any taxes, according to the IRS. What qualifies: Tuition and fees, course-related books, supplies, and equipment. Income: Couples filing jointly who earn less than $160,000; single-filers who earn less than $80,000.

The Lifetime Learning Credit. Students earning less than $60,000 (single-filers) or $120,000 (married, filing jointly), can claim up to $2,000 education-related expenses.

Tuition and fee deductions. Like the American Opportunity Credit, students earning less than $80,000 (single) or $160,000 (married, filing jointly) can deduct up to $4,000 in tuition and fees on their annual tax returns. Use it while you can — this tax break is set to expire at the end of 2013 unless lawmakers extend it.

Student loan interest deduction. If you've taken out a federal or private student loan, you're eligible to deduct up to $2,500 worth of interest paid on the loan as an "above-the-line" exclusion from your income. You don't have to itemize your deductions in order to claim it.

Note: College students can only claim one of the above tax credits per year, but parents supporting more than one child in college can claim tax credits on a per-student basis.